Projects

Skid Mounted Heat/Cool package

A client in Scotland required a single fluid system for heating, cooling and chilling two reactors in a new process.The fluid system had to use existing site services where possible and be situated in a Zone 2 hazardous area. TFS designed 2 Temperature Control Units skids linked to a common expansion tank to operate on Downtherm Q at temperatures between 0°C and 230°C.Each TCU was designed to match the heating and cooling requirements of two very different sized reactors. Both TCU circulated the Heat Transfer Fluid at a constant rate around the reactor jacket during the heating and cooling phases.

Equipment Selection

One TCU was designed to heat using steam to 130°C then up to 230 using an electric heater. First stage cooling was achieved in a heatexchanger using tower water and the final cooling was achieved using bone at -17°C in a titanium plated heat exchanger. TCU2 had eletric heating only with cooling using tower water.

Process Description

Both TCU were designed to ensure heating and cooling of teh reactors was aachieved in the specified time . To enable the TFS supplied the control systems panels located in a safe area. The controls switched each heating and cooling reginne brine to ensure the minimum processing times were met.

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Improving Performance in the North West

The multi-reactor contract chemical in­stallation operates with heat transfer fluid in the range from -20°C to +200°C. Thermal Fluid Systems Ltd. carried out a detailed consideration of the operation of an existing installation which was not performing to specifica­tion. Recommendations were made to the client including reselection of the heat transfer fluid, optimisation of recirculation rates to allow more effective heat transfer at the process even at the lowest temp­eratures and changes to the methods of control. The client placed an order for the work to be carried out and the system now operates with increased efficiency, better control and gives increased out­puts from the stainless steel and glass lined reactors. At the same time, fluid flows to condensers have been increased to maintain higher condensation rates in-line with the higher distillation rates achievable in the reactors.

Improvement :The fluid in oil-bath type glass reactors has also been changed to give better response times, higher operating temper­atures and improved control.

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Multiple Heater Installation

A leading manufactured of packing materials decided to switch his old heaters to more efficient and reliable heaters. New dual fuel Bertrams heaters were installed in stages to minimise downtime because the process was contineous. TFS also undertook the piping modifications of the HTF lines to accomodate the new heaters.

Process : It was decided as part of an updating and extension of their facilities to install a number of individual Heaters dedicated to particular groups of presses. They now have three gas fired Thermal Fluid Heaters, each rated at 350kw and each feeding fluid to two or three presses.

Overall, the system has resulted in more efficient operation and increased output per press. The customer now has the potential to further increase productivity on each line and to supply their clients' needs with fewer presses being needed to manufacture a particular component.

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Therminol '66' to 350°C

For the indirect heating of a process reactor vessel, the customer required heat transfer fluid to be available at temperatures up to a maximum of 350°C. At the time of the original design full data was not available to allow operating temperatures etc. to be fixed and some flexibility had to be built into the system design. Since the installation required a liquid phase system, rather than design for operation under pressure, it was decided to propose a system using Solutia Therminol 66.

Design : The 60 Kw Flameproof Electric Thermal Fluid Heater can operate at up to 350°C and in order to maximise fluid life, the system was provided with fully modulating control [thyristor], high fluid flow rate and was designed for the lowest practical film temperature below the manufacturer's recommended maximum of 375°C. Also, the system was designed with a hot seal pot to allow operation without a nitrogen blanket on the expansion tank.

Process : During commissioning the optimum operating conditions were fully established and multiple proving runs were carried out to establish repeatability and product quality. The plant has now been in operation on a continuous basis for over five years without problems and is still using the original charge of Therminol 66 fluid. Overall, the system has resulted in more efficient operation and increased output per press. The customer now has the potential to further increase productivity on each line and to supply their clients' needs with fewer presses being needed to manufacture a particular component.

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Dowtherm Q at 300°C

Introduction

A leading supplier of high quality specialist plastic products needed a new thermal fluid installation to provide heating and cooling of various autoclaves operating at medium and very high pressures. This was customer carried out a detailed assessment of potential suppliers of equipment and selected Thermal Fluid Systems on the basis of our experience with a full range of heat transfer fluids operating over a very wide band of temperatures and on the understanding and attention given to the clients process requirements.

Equipment Selection

Those Autoclaves that require heating only have internal coils and rely on natural convection to heat the batches of product arranged on trays in each Autoclave. The Autoclaves that need to be heated and cooled operate at high pressures and heating and cooling of product is achieved by forced convection using very high pressures recirculating via an external heat exchanger. Until now the heating of the recirculating gas and hence, the processes, have been limited by the maximum temperatures which could be achieved using steam heating. At the same time the final cooling of the Autoclaves was extended by the compromised design of the external heat exchanger. To achieve the desired performance, a fluid would be needed which could be heated to above 300°C and also cooled to 10°C while still being capable of good heat transfer performance. Thermal Fluid Systems considered all the available heat transfer fluids and concluded that the most suitable for this operation would be Dowtherm Q. The fluid has an atmospheric boiling temperature of 267°C and to be able to operate up to 310°C requires the system to be pressurised. As always, such systems require careful attention to the design and operation of the pressurising equipment and to the provision of pressure relieving safety devices.

Installation

The total system was installed in several phases allowing for changes in processing needs as the facility develops. At present the installation has three Bertrams Thermal Fluid Heaters each with dual fuel firing, two rated at 1700 Kw and one at 2700Kw intended for normal operation on Dowtherm Q at 300°C but designed for temperatures up to 320°C.
Each Heater has a Saacke Burner with gas train, controlled by a sophisticated burner and system management package utilising a Saacke controller and a fully enunciated Control Panel. The high efficiency Heaters are of a well proven design and demonstrate the depth of Bertrams experience in the manufacture of Thermal Fluid Heaters.
Fluid circulation in all parts of the plant is by AIIweiler Pumps specifically designed for the pumping of heat transfer fluids. This particular type is able to handle low viscosity synthetic fluids at high temperatures and has a mechanical seal. Standard type heating/cooling sub-loop packages are provided for those Autoclaves which require heating and cooling and these maintain constant flows through the fluid/nitrogen heat exchangers; the recirculating fluid temperature is varied to suit the process requirements on each Autoclave. On each package the fluid is cooled in ITT Shell & Tube Heat Exchangers built to ASME VIII Div 1 with ASME U Stamps and designed and selected by Thermal Fluid Systems to achieve effective heat transfer at the lowest required processing temperatures.

Process Description

Fluid is distributed to the process users from flow and return manifolds in the heater house via a ring main supplying the various autoclaves. Some autoclaves are heated direct from the ring main through a temperature control valve. Some of the autoclaves require cooling as well as heating. On these sub-loops, heating of the fluid is controlled by bleeding in hot fluid from the primary ring main; cooling is achieved by controlling fluid flow through the shell and tube heat exchanger on each skid while inflow from the primary hot ring main is closed off. The customer has found that with the new installation cooling times on the high pressure autoclaves can be significantly reduced compared with what was previously possible. The total installation was designed, installed and commissioned by Thermal Fluid Systems and overall its performance has more than achieved the client's best expectations.

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